Apparatus for grinding drills



Feb. 3, 1925.

C. RABUT APPARATUS I FOR GRINDING DRILLS Filed Nov. 19, 1920 3 Sheets-Sheet 1' ATTORNEYS- Feb. 3, 1925.

c. RABU'I APPARATUS FOR GRINDING DRILLS Filed NbvQ 19, 1920 s Sheets-Sheet 2 I RNEYS Feb. 3, 1925. 1,524,672-

c. RABUT APPARATUS FOR GRINDING 'DRILLS Filed No). 19, 1920 s Shqts-Sheet s mum INVENTOR Patented Feb. 3, 1925.

,UNITEDQSTATES PATENT OFFICE.

CHARLES RAIBUT, or vxnnmnsssun mnrmn, rmcn.

APPARATUS FOR GRINDING DRILLS.

Application filed November 19, 1920. Serial No. 425,035.

in Apparatus for and I do hereby declare This invention relates to an improved apparatus more particularly designed for grinding twist drills, the chief object of which is,to provide an apparatus for grinding drills of various sizes theoretically correct and by the most inexperienced persons.

Referring to the drawings:

Figure 1 is a general plan view of the apparatus adapted for use with an ordinary grindstone Fig. 2 is a face view of the sliding carriage which supports the drill;

Figs. 3 and 4 show respective sections, on lines A-A and B-B of Fig. 1.;

Fig. 5 shows the drill holder in elevation I as seen from'the side in the direction of the arrow in Fig. 1;

Fig. 6 shows in section two jaws of the drill holder with their springs in' position;

Fig. 7 represents the drill holder with a guide or gauge engaged in a groove, the purpose of which is to determine the length and position of the drill; and 1 Figs. 8 and 9 show a modified construction wherein my apparatus is mounted upon a specially designed grindstone frame. The apparatus comprises a carriage having a sliding member 1, which supports a drill holderjto be pushed against the grindstone by means of a screw 2' turning in a bearing on the slide t-hreaded inthe ,fixed 'mem'ber 2" of the carriage. The fixed member 2 of thecarriage is provided with 2. depending stud 3 which may' engage a suitable bearing provided on the frame ofany grinder. -1 I The sliding member 1 is provided with a transverse hole in'which rotates a shaft 4 to oneend of which is keyed an arm 5 extending obliquely from the shaft and forming asupport for a sleeve 6 containing the drill holder 7. This sleeveis held pivotally to the arm 5 by a screw 8 which j ointly with a spring washer 9 insures proper friction.

have invented certain new and" bea full, clear, and exact A lever 10 pivoting on a screw 11 provided with a stud 12, extends through v acutaway portion of ar1n5 and enters-a slot 121, out in the sleeve 6. The opposite end of the lever 10 is in the shape of graduated sector S, which graduations correspond either in millimeters or inche to the diameter of the drill to be ground. posite face of the sector 10 is provided with indentations w'h'ich engageka beveled edge 6 formed on the web of the arm 5, as shown in Fig. 4, to hold the sector 10 in its ad-' justed position. The object of this movejusted around the pin 8 as: a center, is to vary the angle of the cutting lip of the drill..

' The chu ck.7 is composed of four jaws 13 which tend to separate from each other 'underthe action of the springs-l4. These jaws are suitably beveled at their ends I in parallel directions and are evenly held apart from each other by means of two Washers 15 and 16, the latter having grooves in which the jaws are free to slide. "The rear ends of the jaws 13 are beveled and coact with the slots in the washer 16, while the forward beveled ends of the jaws ooact with the interior cone of the chuck-thereby causing the drill to be tightened when,

the screwplug 17 is rotated to press against thejaws 13 through the interposed washers 18 and 19. In order to reduce friction, one

of the washers is preferably made of fibre.

The drill chuck 7 enters freely into the sleeve 6 and is held in place by a pawl 20 in a circular groove C in the walls of the chuck, whereby the drill chuck is free to rotate without longitudinal play. Another pawl 21 is positioned to engage either of two longitudinal grooves .L and I] diametrically opposite to each other, whereby the position of the chuck may be altered through 180 degrees when grinding drills with two cutting edges. The pawl 21 is beveled and the. groove L and L are also beveled on one side, whereby the drill chuck is permitted rotation in one direction in orden to turn the chuck for grinding the second edge without withdrawing the chuck from the sleeve. Two springs 22 held in place by a screw 23, serve to the chur.

At the free end of the shaft 4 is placed a sleeve 24 held upon the shaft 4 by e. screw" he oppress the pawls 20 and 21 against -ment which causes the sleeve 6 to be adwill have an angle of 59 its raised position, to which position the arm inust be adjusted in order for the sleeve 6 to be rotated when the second cutting edge is to be ground. Stops 27 and 2.8 limit the movement of the arm 5 to about 10 degrees above and 45 degrees below its axis of rotation.

The device is also provided with a guide or gauge 29 which, when held in the two longitudinal grooves L and L of the drill chuck, serves to determine the length to which the drill is to protrude from the holdr and also the position of its cutting edges. Graduations and other indications marked on the gauge and on the chuck indicate the different diameters of the drills to be sharpened.

In operating the apparatus described, the carriage is placed in such manner that the shaft 4 is in parallel positionwith the shaft of the grinding wheel and the drill is positioned so that it protrudes the proper distance indicated by the gauge 29. The sector is then adjustedto a position to give the desired angle to thecutting edge of the drill, for instance, such that the cutting edges degrees with ,the axis and a slope-of 12 degrees, a condition recognized in practice to be satisfactory for the majority of cases! The arm 5 will then be lowered into the proper plane with relation to the stone and the drill will be ground exactly-to the angle determined by the adjustments. The screw 2 may be adjusted as the grinding proceeds to maintain the -necessary contact between the stone and the drill.

From the preceding it is easily seen that by varying any of the three positions any desired cutting edge may be obtained which in some cases may be more satisfactory to the metal to be worked.

Instead of designing the carriage for attachment to the usual machine shop grindstones, I may supply the grindstone and drill-holding device in a single unit, as shown in Figs. 8 and 9. This apparatus comprises a frame 30 supporting a freely rotating" shaft 31 to which two grindstones 32 and' 33 are attached, the latter having a cylindrical surface for coacting with the drill to be ground. 1

The sleeve 6 and chuck, etc. are identical with the parts previously described, and the sleeve is similarly supported by mechanism not shown upon an arm 34 attached to the end of the shaft 35 fixed in the uppef ends of two arms 36 forming with their connectmg web. a swinging frame supported atits lower end uponpivot pins set in cats proectlngfrom the edge of the main frame 30. Springs 37 tend to draw the swinging frame toward the frame 30 and an adjusting screw 38 threaded through the web of the swingmg frame limits t e movement to the position desired.

i saac'za One of the more important advantages of this construction is that the springs 37 hold the frame36 at its extreme inwardposition thereby enabling a uniform cutting action upon the drill irrespective of the wear or back-lash of the threads on the screw 38. Furthermore the tension of the springs enables the frame to move outward ly relative to the grinder when too much pressure towards the grinder is exerted by the operator, thereby avoiding the break- 1. In a"- drill grinding apparatus, a rotat-' able grinder. a frame adjustable toward and away from the grinder, and a chuck carrying arm pivoted on said frame and extending outwardly at an angle to the axis of rotation of the grinder, in combination with means for supporting a drill chuck on said arm for bodily rotation about its longitudinal axis and for bodily rotation about a second axis arranged at an angle to the plane of rotation of the grinder.

2. In a drill'grinding apparatus, a rotatable grinder, a frame adjustable toward and away from the grinder, a chuck carrying arm pivotally connected tosaid frame and extending outwardly at an angle to the axis of rotation of said grinder, in combination with means for supporting a drill chuck. on said arm, said means comprising a member in which the chuck is mounted to rotate about its own axis and means for pivotally connecting said member to said arm upon a second axis arranged at an angle to theplane of rotation of the grinder.

Q In a drill grinding apparatus, a rotatable grinder. a frame adjustable towards and away from the grinder, and a chuck carrying arm pivotally connected to said frame and extending outwardly at an angle to the axis of rotation of said grinder, in 'combination with means for supporting a drill chuck on said arm. said means comprising atmember in which the chuck is mounted to rotate about its own axis, means for locking said chuck against reverse rotation in any predetermined position, and means for movably connecting said member to said arm to vary the slope, of the cutting lipof the drill. 4. In a drill grinding apparatus, a r0tatable grinder, a frame adjustable towards andiaway from the grinder, and a chuck carrying arm pivotally connected to said frame and extending outwardly at an angle loo to the axis of rotation of said grinder, in combination with means for supporting a drill chuck on saidarm. said means comprising a member in which the chuck is' mounted to rotate about its own axis, meansv for locking said chuck against reverse rotation in any predetermined position, means for pivotally connecting said member to said arm to rotate in a plane arranged at an angle to the plane of the grinder, and a sector means for moving said member about its-pivot to indicate the desired angle to be given to the cutting edge of the drill.

5. In a drill grinding apparatus, a rotatable grinder, a frame adjustable towards and away from the grinder, and a chuck carrying arm pivotally connected to said frame and extending outwardly. at an angle to the axis of rotation of said grinder in combination with means for supporting a drill chuck on said arm, said means comprising-a member in which the chuck is mounted to rotate: about its own axis, means for pivotally connecting said member to said arm,a sector means ivoted to said arm to indicate the angle to e given to the cutting edge of the drill, and means secured to the sector and engaging said member to move the latter about its pivot by a movement of the sector means. j

6. In a drill grinding apparatus, a rotatable grinder, a frame adjustable towards and away from the grinder, and a chuck carrying arm pivotally connected to said frame and extending outwardly at an angle to the axis of rotation of said grinder, in combination with means for supporting a drill chuck on said arm' comprising a member in which the chuck is removably mounted to rotate about ,its longitudinal axis, meansgfor pivotally connecting said member tosaid arm to rotate the same about a second axis arranged at an angle to the lon itudinal axis of: the chuck, and means for rotating said'chuck about said second axis comprising. a sector pivoted/to saidarm and.

provided with mechanism for engaging said member to move the latter by movement of said sector, and means on said sector coop:

erating with means on said arm for-holding said sector in adjusted position.

7 .-In a drill grinding apparatus, a rotatable grinder, a frame adjustable towards and away from the grinder, and a chuck carrying arm pivotally connected to said frame and extending outwardly at an angle to the axis of rotation of said grinder, in combination with means for supporting a drill chuck on said arm comprising a member in which the chuck is removably mounted to rotate about means for pivotally connecting said member to said arm to rotate the same about a second axis arranged at an' angle to .the

its' longitudinal axis,

and away from the grinder, and a chuck carrying arm pivotally connected to said frame and extending outwardly at an angle to the axis of rotation of said grinder, in combination with means for supporting a drill chuck on said arm comprising a member in which the chuck is removably mounted to rotate about its longitudinal axis, means for pivotally connecting said member to said arm to rotate the same about a second axis arranged at an angle to the' longitudinal axis of the chuck, and means for rotating said chuck about said second axis comprising a sector pivoted to said arm and provided with mechanism for engaging said member to move the latter by movement of said sector, and means on said sector cooperating with means on said arm for holding said sector in adjusted position, said arm being provided with a slot in which said mechanism operates, the ends of said slot serving to limit the movement in either direction of said chuck about its second axis. .9. In a drill grinding apparatus, a rotatable grinder, a frame adjustable towards and away from said grinder, a shaft cara plane at an angle to the plane of rotation of said grinder, and means for enabling the chuck to be tilted or'moved in this plane relative to the arm.

10. In a drill grinding apparatus, a rotatable grinder, a frame adjustable towards and from the. grinder, a chuck carrying arm pivoted to said frame, a chuck, means carried by saidl'arm for supporting said chuck at an angle to the axis of rotation of the grinder for giving" the desired angle to the cuttin edge of the drill and for bodily rotation a out an axis arranged at an angle to the plane of rotation of the. grinder to vary the slope to be given to the cutting lip of the drill.

In testimony whereof I aflix my signature. 

